Method of manufacturing a planar coil construction

ABSTRACT

A planar coil construction, especially adapted for use in a force-producing device such as a de-icer, includes first and second sheet-like members, each defined by a continuous electrical conductor having a plurality of turns and first and second ends. The first end of the first conductor defines an electrical input to the coil, while the second end of the second conductor defines an electrical output from the coil. The second end of the first conductor and the first end of the second conductor are electrically connected. The sheet-like members are superimposed such that current flow through adjacent turns of the conductors is in the same direction. Within each sheet-like member, adjacent conductors also have current flow in the same direction. The invention includes a technique for spacing the conductors by means of a dielectric layer, and a technique for encapsulating the sheet-like members. Alternative embodiments are provided wherein different relationships among the sheet-like members are possible as they might be used for force-producing elements in a de-icer.

CROSS-REFERENCE TO RELATED PATENT

This application is a division of application Ser. No. 07/437,489, filedNov. 15, 1989, now U.S. Pat. No. 4,875,644, issued Oct. 24, 1989 byLowell J. Adams et al., entitled "PLANAR COIL CONSTRUCTION."

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to planar coils and, more particularly, to planarcoils especially adapted for use in a force-producing device such as ade-icer.

2. Description of the Prior Art

The accumulation of ice on aircraft wings and other structural membersin flight is a danger that is well known. As used herein, the term"structural members" is intended to refer to any aircraft surfacesusceptible to icing during flight, including wings, stabilizers, engineinlets, rotors, and so forth. Attempts have been made since the earliestdays of flight to overcome the problem of ice accumulation. While avariety of techniques have been proposed for removing ice from aircraftduring flight, these techniques have had various drawbacks that havestimulated continued research activities.

One approach that has been used extensively is so-called mechanicalde-icing. In mechanical de-icing, the leading edges of structuralmembers are distorted in some manner so as to crack ice that hasaccumulated thereon for dispersal into the airstream. A popularmechanical de-icing technique is the use of expandable tube-likestructures that are periodically inflatable. Inflation of the structuresresults in their expansion or stretching by 40% or more. Such expansiontypically occurs over approximately 2-6 seconds and results in asubstantial change in the profile of the de-icer, thereby crackingaccumulated ice. Unfortunately, expansion of the devices can negativelyinfluence the airflow passing over the aircraft structure. Also, theyare most effective when ice has accumulated to a substantial extent,approximately 0.25 inch or more, thereby limiting their effectiveness.Desirably, ice removal would be accomplished long before accumulationsapproximating 0.25 inch have been attained.

A more recent mechanical de-icing technique utilizes internal "hammers"to distort the leading edges of structural members. Such an approach isexemplified by U.S. Pat. No. 3,549,964 to Levin et al., whereinelectrical pulses from a pulse generator are routed to a coil of aspark-gap pressure transducer disposed adjacent the inner wall of thestructural member. The primary current in the coil induces a current inthe wall of the structural member and the magnetic fields produced bythe currents interact so as to deform the member.

U.S. Pat. Nos. 3,672,610 and 3,779,488 to Levin et al. and 4,399,967 toSandorff disclose aircraft deicers that utilize energized inductioncoils to vibrate or torque the surface on which ice forms. Each of thesedevices employs electromagnetic coils or magneto-restrictive vibratorslocated on the side of the surface opposite to that on which iceaccumulates. In U.S. Pat. No. 3,809,341 to Levin et al., flat buses arearranged opposite one another, with one side of each bus being disposedadjacent an inner surface of an ice-collecting wall. An electric currentis passed through each bus and the resulting interacting magnetic fieldsforce the buses apart and deform the ice-collecting walls.

A more recent approach is shown by U.S. Pat. No. 4,690,353 to Haslim etal. In the '353 patent, one or more overlapped flexible ribbonconductors are imbedded in an elastomeric material that is affixed tothe outer surface of a structural member. The conductors are fed largecurrent pulses from a power storage unit. The resulting interactingmagnetic fields produce an electro-expulsive force that distends theelastomeric member. The distension is almost instantaneous when acurrent pulse reaches the conductors, and is believed to be effective inremoving thin layers of ice. Although the device disclosed in the '353patent is believed to be an improvement over previous mechanicalde-icing techniques, certain drawbacks remain. One of the drawbacksrelates to the direction of current flow in adjacent electricallyconductive members. It is believed that the current flow disclosed inthe '353 patent produces inefficiencies that significantly restrict theeffectiveness of the device.

The Electro-Repulsive Separation System Patent discloses a device thatis an improvement over that disclosed in the '353 patent. In theElectro-Repulsive Separation System Patent, the electrically conductivemembers are arranged with current flow in a common direction in aconductor layer such that a greater electro-expulsive force can begenerated than with the serpentine configuration disclosed in the '353patent. Also, the Electro-Repulsive Separation System Patent teaches thedelivery of a current pulse of predetermined magnitude, shape andduration that provides more effective de-icing action.

Despite the advances taught by the prior art, particularly theElectro-Repulsive Separation System Patent, there remains a need for ade-icer that provides effective de-icing action. A particular concernrelates to the electrically conductive members that are used with theprior devices. It is desired to provide coils that are as thin aspossible, while being relatively inexpensive and easy to manufacture.Desirably, any such coils would have a very high efficiency, that is,they would generate more force than prior electrically conductivemembers for a given current input. The coils also desirably would permita small or large area of force production as desired for a de-icerconstruction.

SUMMARY OF THE INVENTION

The present invention addresses the foregoing concerns and provides anew and improved planar coil construction especially adapted for use aspart of a de-icer. The planar coil according to the invention includes afirst sheet-like member defined by a first, continuous, electricalconductor having a plurality of turns and first and second ends. Thefirst end of the first conductor defines an electrical input to thecoil, and the second end of the first conductor defines an electricaloutput. The invention includes a second sheet-like member defined by asecond, continuous, electrical conductor having a plurality of turns andfirst and second ends. The first end of the second conductor defines anelectrical input, and the second end of the second conductor defines anelectrical output from the coil. The second end of the first conductorand the first end of the second conductor are electrically connected.The first and second sheet-like members are disposed parallel to eachother with the turns of the first and second conductors being positionedadjacent each other. The direction of current flow through the turns ofthe first conductor can be arranged to be substantially the same as thatthrough the turns of the second conductor, or it can be arranged to besubstantially opposite that through the turns of the second conductor.In addition, within a sheet-like member the adjacent conductors from thecenter out have current flow in the same direction, which is ofparticular importance for electro-repulsive force de-icers.

In one embodiment of the invention, the turns are rectangular, while inother embodiments the turns are spiral-shaped, square, or any otherdesired geometry. The invention also includes a technique for separatingthe sheet-like members by a dielectric layer, as well as a means forencapsulating the sheet-like members. Additional sheet-like members canbe provided, if desired, and connected to each other and to the firstand second sheet-like members. When more than two members are used, ifthe direction of current flow in a given layer is opposite to thedirection of current flow in adjacent layers, a strong repulsive forceis created when a high current pulse is applied. If the direction ofcurrent flow in a given layer is in the same direction as in adjacentlayers, it may be used for an eddy current de-icer. The invention alsocontemplates incorporating a ferromagnetic or paramagnetic material(hereinafter referred to as "magnetic material") on the outer and/orinner surface of the coil in order to improve or shape the magneticfield generated by the coil and increase the resultant force.

Regardless of the embodiment of the invention that is utilized, thesheet-like members can be manufactured readily from metal foil or aflat-braided conductor. The coil according to the invention can beassembled readily, and it provides significant force-generatingcapabilities compared with prior coil constructions.

The foregoing and other features and advantages of the present inventionwill become more apparent when viewed in light of the description of thebest embodiment of the invention and the drawings that follow, whichtogether form a part of the specification.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a sheet-like member formed of a continuouselectrical conductor that is usable with the present invention;

FIG. 2 is a view similar to FIG. 1, showing another sheet-like member;

FIG. 3 is a view similar to FIG. 1, showing the sheet-like members ofFIGS. 1 and 2 completely superimposed;

FIG. 4 is a view similar to FIG. 3, showing a first superimposed pair ofsheet-like members partially superimposed with respect to a second pairof superimposed sheet-like members;

FIGS. 5A and 5B are schematic cross-sectional views of planar coilsaccording to the invention as they might be used in a de-icer;

FIG. 6 is a plan view of an alternative embodiment of the sheet-likemember of FIG. 1;

FIG. 7 is schematic, cross-sectional view of an assembled coilconstruction employing four superimposed sheet-like members;

FIG. 8 is a plan view of the coil construction of FIG. 7, with thesheet-like members displaced relative to each other for clarity inillustrating the directions of current flow;

FIGS. 9A-9F are cross-sectional views similar to FIG. 7 showing howplanar coils according to the invention can be assembled for use as aforce-producing element as part of a deicer;

FIG. 9G is a cross-sectional view of the coils of FIGS. 9A-9F takenalong a plane indicated by line 9G-9G in FIG. 9C; and

FIG. 10 is a plot of force versus current for coils as illustrated inFIGS. 7 and 8.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a planar coil construction especiallyadapted for use as part of a de-icer that may be attached to the leadingedges of structural members. De-icing is the removal of ice subsequentto its formation upon a leading edge. A leading edge is that portion ofa structural member that functions to meet and break an airstreamimpinging upon the surface of the structural member. Examples of leadingedges are the forward portions of wings, stabilizers, struts, nacelles,rotors and other housings and protrusions first impacted by anairstream.

Although the planar coil construction of the present invention isdescribed in the environment of a de-icer, it is to be understood thatthe invention can be used in other environments. For example, theinvention could be used as a force-generating element in a vibratoryconveyor, as a switching device, or in a variety of other applications.Accordingly, the invention as described and claimed herein shall not belimited solely to use in de-icer applications.

Referring to FIG. 1, a first, sheet-like member is indicated by thereference numeral 10. The member 10 is defined by a first, continuous,electrical conductor having a plurality of turns 12, a first end 14 anda second end 16. The first end 14 defines an electrical input to themember 10, while the second end 16 defines an electrical output from themember 10. The member 10 is formed from a single sheet of unalloyedcopper or aluminum having a thickness of about 0.016 inch. The turns 12have a width within the range of 0.070-0.125 inch.

The first end 14 is disposed at one corner of the member 10, while thesecond end 16 is disposed at the center. Although the member 10 isillustrated as being rectangular, it could be square, circular, or anyother desired shape.

Referring to FIG. 2, a second, sheet-like member is indicated by thereference numeral 20. The member 20 is defined by a second, continuous,electrical conductor having a plurality of turns 22, a first end 24, anda second end 26. The first end 24 defines an electrical input to themember 20, while the second end 26 defines an electrical output from themember 20. The member 20 is formed from a single sheet of unalloyedcopper or aluminum having a thickness of about 0.016 inch. The turns 22have a width within the range of 0.070-0.125 inch. As with the member10, the member 20 is rectangular, with one end disposed at a corner andthe other end disposed at the center.

Referring to FIG. 3, the members 10, 20 are illustrated in a "completelysuperimposed" arrangement to form a coil indicated by the referencenumeral 30. In this arrangement, the turns 12 are disposed immediatelyadjacent comparable turns 22. The ends 16, 24 are joined as by solderingor welding to form an electrical connection. As will be appreciated froman examination of FIG. 3, electrical current directed into the first end14 will follow a path through the turns 12 that is in the same directionas the superimposed, adjacent turns 22. The first member 10 typicallyhas 121/8 turns, as does the second member 20. (An 81/8 turn member isshown for clarity of illustration). Accordingly, the superimposedmembers 10, 20 define a coil pair 30 having 241/2 turns.

Referring to FIG. 4, two assembled coil pairs 30 have been formed asshown in FIG. 3, and are "partially superimposed" with respect to eachother. The resultant coil construction, indicated by the referencenumeral 40, includes about 25% of the total turns overlapped at thecenter of the assembled coil pairs 30.

Referring to FIG. 5A, arrangements of two coil pairs 30 are shown asthey might be used in practice to form part of a de-icer. As isexplained in more detail in the Electro-Repulsive Separation SystemPatent, upon supplying a short-duration, shaped, high-current pulse tothe coil pairs 30, the outermost portion of the de-icer will bedistended as indicated at 42 so as to shatter, debond, and expel any icethat may have accumulated thereon. Referring to FIG. 5B, the coil pairs30 are partially superimposed and an enhanced force will be generated inthe region of the overlap where, presumably, the de-icing action will beenhanced. The enhanced distension of the de-icer is indicated by thereference numeral 44.

Referring to FIG. 6, an alternative construction of a sheet-like memberis indicated schematically by the reference numeral 50. The member 50,like the members 10, 20, is defined by a first, continuous, electricalconductor having a plurality of turns 52, a first end 54, and a secondend 56. Unlike the members 10, 20, the second end 56 crosses a portionof the turns 52 and is disposed adjacent the first end 54 at a locationoutside the outermost turn 52. The first end 54 defines an electricalinput to the member 50, while the second end 56 defines an electricaloutput from the member 50. The second end 56 is electrically isolatedfrom the turns 52 that are crossed. The member 50 is formed from asingle sheet of unalloyed copper or aluminum having a thickness of about0.016 inch. The turns 52 have a width within the range of 0.070-0.125inch.

Referring to FIG. 7, an assembled coil construction employing foursheet-like members 50 is indicated schematically by the referencenumeral 60. Pairs of the members 50 are separated by dielectric layers62 as well as the second end 56 of the members 50. The dielectric layers62 preferably are formed of a material such as two layers of polyamidefilm, each having a thickness of about 0.003 inch. A suitable polyamidefilm is available from the E.I. Dupont deNemours & Company under thetrademark KAPTON. Before use, the film should be surface-treated byacid-etching, plasma treating or the like to improve adhesion.

Referring to FIG. 8, the members 50 of the coil assembly 60 are showndisplaced relative to each other for purposes of illustrating thedirections of current flow therein. The uppermost member 50 is shown insolid lines, while the immediately adjacent lower member 50 is shown bydashed lines. As can be seen in FIG. 8, the second end 56 of theuppermost sheet 50 is electrically connected to the first end 54 of theimmediately adjacent lower member 50. The output of the lower member 50is directed through the end 56 to the second end 56 of the lower member50 of the adjacent coil pair. The lower coil pair members 50 areconnected in the same manner as the upper coil pair members 50. However,because the electrical input is to the second end 56 of the lower member50, current flow through the lower coil pairs is in a direction oppositeto that of the upper coil pairs. As shown in FIG. 8, current flowthrough the upper coil pairs is in a clockwise direction, while currentflow through the lower coil pairs is in a counterclockwise direction.Due to the opposing directions of current flow in the upper coil pairand lower coil pair conductors, and because the coil pairs are separatedby the KAPTON film 62, upon supplying a short-duration, high-currentpulse to the coil 60, the respective upper and lower coil pairs will beforcefully displaced away from each other. This would constitute a forceelement for an electro-repulsive type of de-icer.

As in the de-icer schematically indicated in FIG. 5A, the displacementof the coil force elements can be utilized in a de-icer to providede-icing action. If the direction of current flow in the lower coil pairis reversed by electrically connecting the upper coil pair second end 56to the first end 54 of the adjacent lower coil pair, current flowthrough the lower coil pair is in the same direction as that of theupper coil pair. The coil pairs thus may be used in an eddy current typeof de-icer construction.

Referring to FIGS. 9A-9G, a schematic view of planar coils according tothe invention during their manufacture for an eddy current de-icer isillustrated. It will be assumed that the arrangement shown in FIGS.9A-9G incorporates the members 10, 20, although the members 50 could beemployed with equal facility.

In FIG. 9A, the member 10 is illustrated as it is manufactured initiallyin an etching operation. In such an operation, a sheet of unalloyedcopper is attached to a backing sheet 70. The copper sheet is coatedwith a substance, such as a photo-resist material, that is impervious toan etching material such as sulfuric acid. The backing sheet 70 also isimpervious to the acid. Upon applying the acid to the surface of thecopper sheet, copper will be removed in those areas not protected by thephoto-resist material. After the copper in the unprotected areas hasbeen removed, the sheet will take the appearance of the member 10 shownin FIG. 1. The member 10 also could be formed in a stamping operation ora machining operation. If desired, the member 10 could be made from acontinuous flat-braided conductor.

In order to process the member 10 further, it is necessary to remove itfrom the backing sheet 70. This result is accomplished by applying alayer of double-sided tape 72 to the exposed surface of the member 10.The tape 72 has a thickness of about 0.0045 inch. A suitable tape 72 canbe obtained from Fasson Corporation under the trademark FASTAPE A. Uponlifting the tape 72, the member 10 will be removed from the backingsheet 70. The edges of the tape 72 are trimmed to closely approximatethe outer dimensions of the member 10. Thereafter, the exposed adhesiveside of the tape 72 can be attached to a layer of dielectric materialsuch as KAPTON film. The dielectric layer is indicated in FIG. 9C by thereference numeral 74. Similarly, the member 20 can be manufactured in anetching process and removed from its backing sheet 70 by means of asecond layer of double-sided tape 72. Upon attaching the exposed surfaceof the second double-sided tape 72 to the exposed surface of thedielectric layer 74, the sandwiched coil construction 30 shown in FIG.9C will be obtained. As shown in FIG. 9G, the layer 74 extends laterallybeyond the edges of the members 10, 20 and the tape 72 to form a borderapproximately 0.25 inch wide that prevents arcing between the edges ofthe members 10, 20.

In order to protect the members 10, 20 and to provide a dielectriceffect, it is desired that the members 10, 20 be encapsulated in somemanner. Referring to FIG. 9D, the coil assembly 30 of FIG. 9C isillustrated as being sandwiched between layers 76 of a compositematerial such as fiberglass/epoxy. A suitable fiberglass/epoxy materialcan be obtained from Fiberite Corporation under the trademark MXB7669/7781. After the layers 76 are assembled as illustrated in FIG. 9D,the assembled components are placed in a mold where heat and pressurecan be applied so as to conform the coil construction 30 to any desiredcontour. Although the embodiment illustrated in FIG. 9D is flat, acurved contour should be employed if the coil assembly 30 is to beattached to the curved surface of a structural member. During theapplication of heat and pressure to the layers 76, it is expected thatthey will flow at least to a small extent so that gaps between adjacentturns 12, 22 will be filled. The initial thickness of each layer 76 isabout 0.010 inch, and the final thickness of each layer 76 is about0.005-0.006 inch. Also, the edges of the layers 76 will be compressedtoward each other to form a tapered configuration that assists inmatching the contour of the structural member with which the coilassembly 30 is to be used.

Referring to FIG. 9E, the coil assembly 30 of FIG. 9D is shown as itmight be attached to the external surface of a metal structural member78. The innermost fiberglass/epoxy layer 76 is spaced from thestructural member 78 by means of a release layer 80 that permits thecoil assembly 30 to move away from and toward the structural member 78.The layer 80 is very thin (about 0.001 inch) and can be obtained fromthe Richmond Division of Dixico Incorporated under the trademark A5000.A surface ply 82 is positioned over the outermost surface of the exposedlayer 76. The ply 82 is secured to the exposed layer 76 by an adhesivesuch as EA951 commercially available from the Hysol Corporation. If theply 82 is made of metal such as titanium, aluminum or stainless steel,it should be surface-treated for better adhesion. If the ply 82 is madeof a thermoplastic material such as polyetherether ketone (PEEK),surface-treating also is necessary. If the ply 82 is made of anothertype of thermoplastic material, surface-treating may not be necessary. Ametal ply 82 will have a thickness of about 0.005 inch while a non-metalply 82 will have a thickness of about 0.015 inch. The ends of the layers80, 82 are attached to the structural member 78 by bonding or any othersuitable technique. Typically, an elastomeric support (not shown) wouldbe provided at the ends of the layers 80, 82 in order to provide asmooth transition to the contour of the member 78 and to assist insecuring the layers 80, 82 relative to the remainder of the de-icerstructure. Regardless of how the layers 80, 82 are connected to thestructure 78, it is necessary that at least the layer 82 be able to moveaway from, and toward, the structural member 78.

In operation, upon supplying a short-duration, shaped, high-currentpulse to the coil 30, an electromagnetic field will be generated thatwill induce eddy currents in the structural member 78 and to a lesserextent in the thin surface ply 82. The eddy currents then will generateelectromagnetic fields which will tend to repel the electromagneticfield of the coil 30. In turn, the coil 30, with the surface ply 82attached, will be forcefully displaced away from the structural member78. Upon collapse of the magnetic fields, the coil 30 and the surfaceply 82 will be forcefully retracted against the structural member 78 tothat position shown in FIG. 9E. If the structural member 78 is made of acomposite material such as graphite/epoxy instead of metal, a metaltarget (a so-called "doubler") should be disposed on the outside orinside of the member 78.

An additional variation is shown in FIG. 9F. In FIG. 9F, a release layer84 is disposed intermediate the outermost encapsulating layer 76 and thesurface ply 82. Accordingly, the surface ply 82 can move away from, andtoward, the coil 30 upon energization thereof. Because the release layer80 is used in the embodiment shown in FIG. 9F, the coil 30 will moveaway from, and toward, the structural member 78 if the member 78 is madeof metal. If the member 78 is made of a composite material, then thecoil 30 will remain in contact with the outer surface of the member 78.In such a circumstance, it may be desirable to eliminate the releaselayer 80 and bond the innermost encapsulating layer 76 to the member 78by means of an adhesive such as EA951. Regardless of the material fromwhich the member 78 is made, it will be appreciated that the surface ply82 always will be forcefully displaced away from, and toward, the member78 so as to effect a de-icing action.

Referring to FIG. 10, a plot of force versus current is shown for coilsconstructed and arranged as shown in FIGS. 7 and 8 as a force elementfor an electro-repulsive type of de-icer. The tests that were conductedto generate the graph of FIG. 10 were laboratory vice tests in which atransducer was disposed intermediate the adjacent coil pairs 50. Thelower plot indicated by the reference numeral 86 shows that the forceproduced by the coil 60 is a direct function of the current suppliedthereto. The uppermost curve indicated by the reference numeral 88 showsthat disposing a paramagnetic target material (in this case 6061aluminum, having a thickness of 0.060 inch) adjacent the outer surfaceof one of the members 50 produced an enhanced separation force. Thedifference ranges from approximately 19% at lower current levels to 9%at higher current levels. FIG. 10 confirms that coil pairs operating onthe so-called "electro-expulsion" principle such as that disclosed inthe Electro-Repulsive Separation System Patent have excellentforce-generating capabilities, but that such capabilities can beenhanced by the use of a metal target disposed in proximity with thecoils. It is believed that this result is brought about by eddy currentsthat are induced in the target that create an electromagnetic field thatinteracts with the electromagnetic field generated by the coil 60. Ineffect, the magnetic target improves or shapes the magnetic fieldgenerated by the coil 60. It is believed that the plot 86 would berepresentative of the force produced by attaching the coil 60 to acomposite structural member 78, while the plot 88 would berepresentative of the results produced by attaching the coil 60 to ametal structural member 78 or by using a metal surface ply 82 inconjunction with 0.060 inch thick metal targets adjacent the coils.

Although the invention has been described in its preferred form with acertain degree of particularity, it will be understood that the presentdisclosure of the preferred embodiment has been made only by way ofexample, and that various changes may be resorted to without departingfrom the true spirit and scope of the invention as hereinafter claimed.It is intended that the patent shall cover, by suitable expression inthe appended claims, whatever features of patentable novelty exist inthe invention disclosed.

What is claimed:
 1. A method of manufacturing a planar coil constructionfor use in a force-producing device, comprising the steps of:providing afirst, sheet-like member defined by a first, continuous electricalconductor having a plurality of turns and first and second ends, thefirst end of the first conductor defining an electrical input and thesecond end of the first conductor defining an electrical output;providing a second, sheet-like member defined by a second, continuouselectrical conductor having a plurality of turns and first and secondends, the first end of the second conductor defining an electrical inputand the second end of the second conductor defining an electricaloutput; establishing an electrical connection between the second end ofthe first conductor and the first end of the second conductor; disposingthe first and second sheet-like members parallel to each other withselecting turns of the first electrical conductor being positionedadjacent to selected turns of the second electrical conductor such thatthe direction of current flow through the turns of the first conductoris substantially in the same direction as the current flow through theturns of the second conductor, wherein the step of disposing the firstand second sheet-like members parallel to each other is carried out by:providing first and second layers of two-sided tape, each layer being asize and shape to completely overlie the first and second sheet-likemembers; applying the first layer of two-sided tape to a selected sideof the first sheet-like member; applying the second layer of two-sidedtape to a selected side of the second sheet-like member; providing alayer of dielectric material; and attaching the exposed surfaces of thefirst and second layers of two-sided tape to the opposite sides of thelayer of dielectric material.
 2. The method of claim 1, wherein thesteps of providing the first and second sheet-like members areaccomplished by etching, machining, or stamping the conductors from asheet of metal.
 3. The method of claim 1, comprising the additional stepof encapsulating the assembled sheet-like members, tape layers, anddielectric layer, the encapsulation serving as a dielectric andprotecting the sheet-like members.
 4. The method of claim 1, furthercomprising the step of disposing a layer of paramagnetic materialadjacent a selected one of the first or second sheet-like members. 5.The method of claim 3, wherein the step of encapsulating comprises thesteps of:providing first and second layers of a composite material; anddisposing the assembled sheet-like members, tape layers, and dielectriclayer between the first and second layers of composite material.
 6. Themethod of claim 5, wherein the composite material is fiberglass/epoxy.7. The method of claim 5, further comprising the steps of:placing theencapsulated coil construction in a mold having a desired contour; andapplying heat and pressure to the encapsulated coil construction inorder to compress the coil construction and conform it to the contour ofthe mold.
 8. The method of claim 1, wherein the dielectric layercomprises a polyamide film.
 9. The method of claim 1, further comprisingthe step of trimming the edges of the layers of two-sided tape toclosely approximate the outer dimensions of the first and secondsheet-like members prior to the step of attaching the layers oftwo-sided tape to the opposite sides of the layer of dielectricmaterial.
 10. The method of claim 1, wherein the step of providing alayer of dielectric material includes providing a layer of dielectricmaterial of a size and shape such that the dielectric layer extendslaterally beyond the edges of the first and second sheet-like members toform a border adequate to prevent arcing between the edges of the firstand second sheet-like members.
 11. A method of manufacturing a planarcoil construction for use in a force-producing device, comprising thesteps of:providing a first, sheet-like member defined by a first,continuous electrical conductor having a plurality of turns and firstand second ends, the first end of the first conductor defining anelectrical input and the second end of the first conductor defining anelectrical output; providing a second, sheet-like member defined by asecond, continuous electrical conductor having a plurality of turns andfirst and second ends, the first end of the second conductor defining anelectrical input and the second end of the second conductor defining anelectrical output; establishing an electrical connection between thesecond end of the first conductor and the first end of the secondconductor; disposing the first and second sheet-like members parallel toeach other with selecting turns of the first electrical conductor beingpositioned adjacent to selected turns of the second electrical conductorsuch that the direction of current flow through the turns of the firstconductor is substantially in the same direction as the current flowthrough the turns of the second conductor, wherein the step of disposingthe first and second sheet-like members parallel to each other iscarried out by: providing first and second layers of two-sided tape,each layer being a size and shape to completely overlie the first andsecond sheet-like members; applying the first layer of two-sided tape toa selected side of the first sheet-like member; applying the secondlayer of two-sided tape to a selected side of the second sheet-likemember; providing first and second layers of dielectric material;attaching the exposed surface of the first layer of two-sided tape to aselected side of the first layer of dielectric material; attaching theexposed surface of the second layer of two-sided tape to a selected sideof the second layer of dielectric material; and disposing the exposedsurfaces of the first and second layers of dielectric material againsteach other.
 12. The method of claim 11, wherein the steps of providingthe first and second sheet-like members are accomplished by etching,machining, or stamping the conductors from a sheet of metal.
 13. Themethod of claim 11, comprising the additional step of encapsulating theassembled sheet-like members, tape layers, and dielectric layers, theencapsulation serving as a dielectric and protecting the sheet-likemembers.
 14. The method of claim 11, further comprising the step ofdisposing a layer of paramagnetic material adjacent a selected one ofthe first or second sheet-like members.
 15. The method of claim 13,wherein the step of encapsulating comprises the steps of:providing firstand second layers of a composite material; and disposing the assembledsheet-like members, tape layers, and dielectric layers between the firstand second layers of composite material.
 16. The method of claim 15,wherein the composite material is fiberglass/epoxy.
 17. The method ofclaim 15, further comprising the steps of:placing the encapsulated coilconstruction in a mold having a desired contour; and applying heat andpressure to the encapsulated coil construction in order to compress thecoil construction and conform it to the contour of the mold.
 18. Themethod of claim 11, wherein the dielectric layers comprise a polyamidefilm.
 19. The method of claim 11, further comprising the step oftrimming the edges of the layers of two-sided tape to closelyapproximate the outer dimensions of the first and second sheet-likemembers prior to the steps of attaching the layers of two-sided tape tothe exposed surfaces of the first and second layers of dielectricmaterial.
 20. The method of claim 11, wherein the step of providingfirst and second layers of dielectric material includes providing layersof dielectric material of a size and shape such that the layers ofdielectric material extend laterally beyond the edges of the first andsecond sheet-like members to form a border adequate to prevent arcingbetween the edges of the first and second sheet-like members.